TC55da Power steering stiffness

[04Bob]

I recently purchased a used TC55da tractor and was told by the seller that he had run the power steering pump low on oil. The steering was stiff so I replaced the pump. The problem still exists. It steers hard even when the front wheels are raised off the ground. I unhooked the cylinder and it seems to push and pull like it should when the steering wheel is turned. I also tried loosening the pressure line and had very little oil flow. The pump is a used one purchased from salvage. I need to figure out why inadequate assist is not getting to the wheels. Any ideas?

 

[jimmysisson]

Get a pressure gauge into the line and see what you got. Also make sure nothing blocks the hoses. There must have been a reason the PO said it was leaking steering fluid; you may want to find out what that is/was as well. Good luck.
Jim

 

[04Bob]

Hi Jim, Thanks for the response. The seller had fixed the leak but had not addressed the stiff steering. Yesterday, I took the return line off the filter/canister and had my wife momentarily start the tractor. There was a healthy flow of hyd. fluid from the line which leads me to believe that the pump is working properly. The cylinder also seems to move in both directions when it is unhooked from the steering arm. I discovered that the cylinder also moves when the steering wheel is turned with the engine off. The steering box must also help push the cylinder. I told the service manager all the things I tried and he appeared as stumped as I was.

 

[jimmysisson]

With the front wheels off the ground do you notice stiffness turning the front wheels with your hands on the tires? I wonder if there's a seized bearing or similar. Still think you need to test the steering pressure against spec.
Jim

 

[04Bob]

The steering is stiff even when I raise the front wheels off the ground with the loader. I am not sure how to get a pressure guage plumbed into the line or where to find a guage. What if the steering box is not transferring fluid to each side of the cylinder when the wheel is turned? How would I check that?

 

[jimmysisson]

You said the return line had good flow. It the pressure line very little? Something doesn't sound right. If you're sure you have the pressure line, that's where a gauge would get teed in. All materials available from Surplus Center. If you're not sure how to do that, how about getting some help on site? Jim

 

[jimmysisson]

Also reread my second post - can you move the front tires left-right manually holding the tires?
Jim

 

[04Bob]

This morning I unhooked the steering cylinder and raised the front wheels off the ground to see if the cylinder moved when the steering wheel is turned. I discovered that it moved in and out but that the steering was stiff even when the engine was running. There was some assist but very little. The front wheels could be moved and steered by hand very easily. I am going to look for a guage set to tee into the line to check pressure.

 

[04Bob]

I finally got a pressure gauge teed into the high pressure line. It reads 300 lbs pressure when the engine is first started then bumps up to about 600 lbs when I turn the steering wheel right or left. It stays at about 600 lbs pressure even after I turn off the engine. That doesn't seem right to me but I am new to hydraulics.

 

[WM75Guy]

My repair manual test procedure for the TC40DA calls for a pressure of 1450-1520 PSI when turning the wheel. If less it could either be a bad pump or the relief valve is bad or set too low.